D2D Communication Underlay in Uplink Cellular Networks with Fractional Power Control and Fractional Frequency Reuse

Underlaying Device-to-Device (D2D) communications in next generation (5G) cellular networks is a promising technology because D2D can exploit the proximity of communication pairs and reuse existing cellular frequency resources. Although D2D communication has a great potential to improve the capacity and spectral efficiency of the overall system, the interference between D2D user equipment (DUE) and cellular user equipment (CUE) needs to be properly tackled in order to achieve the target performance gains. Fractional frequency reuse (FFR) has been demonstrated as an effective scheme to mitigate uplink interference. Further, uplink power control in a cellular network is a widely employed mechanism to manage interference across the uplink network while improving spectral efficiency. Existing uplink fractional power control (FPC) in LTE trades off reasonably well the cell-edge UE performance with the overall system performance. In this paper, we study the performance of D2D communications underlaying an uplink LTE network which utilizes both FPC and FFR. FPC in such a network is slightly different than the existing FPC mechanism in that it is only applied within certain geographical areas. In such a system, geometry information is exploited to allocate resources so that significant interference reduction can be attained. Coverage analysis is conducted for both CUEs and DUEs by following a mathematically trackable Poisson Point Process (PPP) model. A spectral efficiency study is also presented along with the impact of various uplink parameters on the system performance.